EEVblog 1417 - Alternating Current AC Basics - Part 1

[EEVblog]

Following in from the DC circuit fundamanetals seriis starts the AC circuti fundamentals series. This part 1 looks at:
- What is Alternating Current
- How AC is created using a generator
- Angular Frequency
- The sinusoidal waveform, benefits and downsides
- Average, peak, peak to peak, and RMS waveforms, calculation and conversions.
- Non-sinusoidal waveforms
- Crest factor and its impact on multimeter RMS measurement

[dtmouton]

Some fudging and unsubstantiated claims in the derivations:
1. At 25:41: How can you just normalize the area A to 1? If the amplitude of the waveform is 1V then area A is indeed equal to 1 V rad, but you have to integrate to prove this. You cannot just normalize your problems away!
2. At 30:30L "Squaring doesn't change the wave shape". This statement is not true in general. For instance, squaring a square wave gives a constant.
In the case of a sine wave you have to apply the well-known trigonometric identity:
$$\sin^2(\theta) = \frac{1-\cos(2\theta)}{2}$$
It actually tells us something very special about sine waves, i.e. that squaring a sine wave gives us a sine wave with double the frequency. However, you cannot just make the statement that squaring doesn't change the wave shape without referring to this identity.
3. At 36:14: The crest factor for a sine wave is equal to the square root of 2 which is 1.414 and not .414.